Fuel dip stick C172
Alternatively, you could do this:
Go to your local hardware and grab a suitable piece of timber. I use 2" cover strip it's profile is flat with rounded edges- I find it stows well and easy to mark graduations. Make sure it's long enough to not fall into the tank if you accidentally let go. When the aircraft is reasonably low in fuel take your dipstick and aircraft to the bowser. Place the dip stick into the tank, remove it and mark the line made by the fuel. Don't let it sit for too long as it draws fuel up the timber. Add 5 litres, dip and mark again, repeat this process until the tank is full. The last addition may be less than the 5 litres, but note the amount. The "high tide mark is obviously full, so mark it with the total useable for that tank, the next Mark down will be a quantity equal to full, less the last odd amount added. Now label the remainder of the marks progressively deducting 5 litres. I've made at least 30 dipsticks this way over the years and found them to be sufficiently accurate and saves draining a tank. Also not a bad idea to crest a template on cardboard or paper and store it away in case the original goes missing. I lost one out of a Piper Dakota 15 years ago and recently located it in the baggage compartment of a Tiger Moth when checking a guy out in it. Someone had "borrowed" the dipstick to I've the Tiger mag a tap to release the impulse coupling.